1. Field of the Invention
The present invention relates to a driving control device for an actuator which controls the driving of the actuator for opening and closing an air mix door of an air conditioning device for a vehicle, for example.
2. Description of the Prior Art
Conventionally, there has been known a driving control device for an actuator which controls the driving of the actuator for opening and closing an intake door.
This type of actuator driving control device comprises a driving circuit for driving a DC electric motor and a driving control circuit for controlling the rotation of the electric motor by controlling the driving circuit.
The driving control circuit compares a detected signal of a detecting device which detects the rotation position of the intake door and a targeted value, and controls the driving circuit so as to position the intake door in a targeted position.
The driving circuit of the actuator driving control device is composed of an H bridge circuit 100 for rotating the DC electric motor in normal and reverse directions. The H bridge circuit 100 is composed of four MOS type transistors Tr1 to Tr4, as shown in FIG. 6, for example.
In the H bridge circuit, it has been known that at least two transistors of the four transistors are driven by PWM control (for example, reference to Japanese Patent 3199722).
However, in this actuator driving control device, when the motor is actuated (or is stopped), the output of the electric motor is rapidly changed by turning on (and/or turning off) the MOS transistors, Tr1 to Tr4, of the H bridge circuit 100. Consequently, there has been a problem that noise is generated by backlash of a gear, and the noise is offensive to ears, because especially in recent years, a sound of an engine has been reduced, and an interior of a car has become increasingly noiseless.